外文翻譯---利用農業(yè)廢棄麥稈去除含油廢水中的乳化油 英文

1、Biochemical Engineering Journal 49 (2010) 78–83Contents lists available at ScienceDirectBiochemical Engineering Journaljournal homepage: www.elsevier.com/locate/bejRemoval of emulsified oil from oily wastewater using agr

2、icultural waste barley strawShariff Ibrahim, Shaobin Wang ?, Ha Ming AngDepartment of Chemical Engineering, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australiaa r t i c l e i n f oArticle history:Re

3、ceived 12 March 2009Received in revised form23 November 2009Accepted 24 November 2009Keywords:Modified barley strawAgricultural byproductEmulsified canola oilCationic surfactanta b s t r a c tAn agricultural byproduct, b

4、arley straw, was chemically modified by a cationic surfactant, hexadecylpyri-dinium chloride monohydrate (CPC) and employed as an adsorbent to remove emulsified canola oil fromaqueous solution. The textural and surface p

5、roperties of the surfactant modified barley straw (SMBS)were characterized by N2 adsorption, FT-IR, SEM, surface acidic/basic groups and surfactant desorption.The low desorption of CPC from SMBS demonstrated a strong bon

6、ding of the CPC to straw surface. Severalfactors such as adsorption temperature, solution pH, loading of adsorbent, and particle size on oil adsorp-tion were investigated. It was found that addition of CPC created a non-

7、polar layer on barley straw surfacethus endowing SMBS with much better adsorption capacity for oil removal from water. The adsorptionwas found less favorable at high acidic condition and the maximum adsorption capacity w

8、as observedat about neutrality. Larger particle size would result in lower adsorption while adsorption temperaturewould not affect oil adsorption significantly. The kinetic study revealed that equilibrium time was shorta

9、nd the isotherm study indicated that the oil adsorption was fitted well by the Langmuir model. Theadsorption capacity determined from the Langmuir isotherm was 576.0 ± 0.3 mg g?1 at 25 ?C.© 2009 Elsevier B.V. A

10、ll rights reserved.1. IntroductionWater pollution by oil has left an undesired impact on theenvironment. The presence of oil in water not only induces detri-mental effects to aquatic life but also causes serious problems

11、 towastewater treatment plants [1,2]. Generally, oil causes water con-tamination in two forms, as free oil and emulsified oil. Free oil is nota big issue, since the oil can be separated by gravitation and thenskimmed off

12、; however, emulsified oil poses a real problem due to itsstability in the aqueous phase [3]. Oil emulsions exist in effluentsfrom various sources such as petroleum refineries, rolling mills,chemical processing and manufa

13、cturing plants [4]. Various meth-ods for oily wastewater treatment including physical, biological,chemical, mechanical and physicochemical methods (i.e. flotation),and membrane processes have been developed [4]. However,

14、 thereare many limitations for those treatments, such as low efficiency,high operation cost, corrosion and recontamination, etc. [1].Adsorption process is one of the interesting methods for remov-ing organic and inorgani

15、c pollutants in waterway systems [5]. Dueto low efficiency and high cost of activated carbon for oily wastew-ater treatment [6], the possibility of using inexpensive materialsas alternatives was explored by many research

16、ers in the past years[2,7,8]. We conducted a preliminary study of using raw barley straw? Corresponding author. Tel.: +61 8 9266 3776; fax: +61 8 9266 2681.E-mail address: Shaobin.wang@curtin.edu.au (S. Wang).as an adsor

17、bent to remove emulsified oil from an aqueous solution.However, the barley straw was found to show poor efficiency foroil removal. This was expected as raw agricultural waste usuallyexhibited low sorption capacity [9] an

18、d, therefore, modification ofthe raw material seems necessary to boost its performance. Theavailability of specific functional groups such as hydroxyl (–OH) inbarley straw [10] makes it easy to undergo surface modificati

19、on.Some investigations have been reported to show the effective-ness of surfactant modification on inorganic and organic materialsfor emulsified oil adsorption [7,8,11]. The surfactant modifiedadsorbents also showed good

20、 removal of other contaminants suchas metals [12,13], dyes [14,15] and organics [16–19]. In the pre-vious years, the modification was mostly performed on mineralsurface [16,20,21] and only a few applications on agricultu

21、ralwaste/byproduct were reported [11,22].In this work, an agricultural waste, barley straw, was treatedwith a cationic surfactant, hexadecylpyridinium chloride monohy-drate (CPC, C21H38NCl), for oil adsorption. The catio

22、nic heads ofthe surfactant provide an electrostatic driving force for adsorptionon oppositely charged surface [23] thus forming a hydrophobiclayer on the solid surface, which subsequently allows an organiccontaminant par

23、tition into the layer [24]. This is known as adsolubi-lization; a combination of adsorption and solubilization [21]. Alther[7] reported the applicability of surfactant treated clays (organ-oclay) for removal of emulsifie

24、d oil in wastewater. He found thatthe modification with a surfactant produced a hydrophobic, non-polar layer, which subsequently allowed oil droplet partition into1369-703X/$ – see front matter © 2009 Elsevier B.V.

25、All rights reserved.doi:10.1016/j.bej.2009.11.01380 S. Ibrahim et al. / Biochemical Engineering Journal 49 (2010) 78–83Table 1Characteristics of RBS and SMBS.Analysis RBS SMBSSBET (m2 g?1) 95.79 ± 2.21 75.70 ±

26、3.03Pore volume (ml g?1) 0.060 ± 0.02 0.044 ± 0.05Surface acidic groups (mmol g?1) 3.35 ± 0.20 3.18 ± 0.16Surface basic groups (mmol g?1) 0.45 ± 0.02 0.47 ± 0.04Desorption of CPCDeionized wa

27、ter (%) – 2.6 ± 1.100.0001N HCl (%) – 0.37 ± 0.050.001N HCl (%) – 35.0 ± 2.010.01N HCl (%) – 41.4 ± 1.353. Results and discussion3.1. Characterization of adsorbent SMBSPhysicochemical properties of RB

28、S and SMBS are presented inTable 1. BET surface area and pore volume were found to decreaseafter surfactant modification of RBS. This was due to the attach-ment of surfactant moieties to the internal framework of rawbios

29、orbent causing the constriction of pore channels [22]. A reduc-tion in acidic groups on SMBS indicated the involvement of thesegroups in adsorption of CPC+ ions, whereas an increase in basicgroups was due to the uptake o

30、f CPC+ ions. A similar observationwas also reported by Namasivayam and Sureshkumar [22] on coirpith modification. The desorption of CPC was lower at 2.6 ± 0.7%in deionized water indicating a strong bonding between t

31、he CPCand straw surface. However, the desorption of CPC was increasedin acid solutions with a percentage increasing from 2.6 ± 0.7% to41.4 ± 1.1% when initial HCl concentration was increased from0.0001 to 0.01

32、M. Lower pH solution is believed to increase thepositive charge on adsorbent surface [32] thus promoting the des-orption (due to the electrostatic repelling) of positively charged CPCions from the adsorbent surface. The

33、increasing desorption of CPC inan acid solution also suggests that ion exchange is the major bind-ing mechanism [33]. Fig. 1 shows SEM photos of SMBS at differentmagnifications. It is seen that the particle size of the p

34、repared SMBSis showing irregular shapes with particle size less than 500 nm. Thesurface of SMBS presents porous structure with round holes on thesurface.The FT-IR spectrum of SMBS is illustrated in Fig. 2. The spectrumco

35、ntains several peaks, which can be assigned to: C O stretch-ing mainly from carboxylic and traces of ketones and esters (at1712 cm?1), OH stretching vibrations of H-bonded hydroxyl groupsof phenol (at 3418 cm?1), C–O str

36、etching (at 1032 cm?1), CH3 weakstretching (at 2922 cm?1), peaks of OH-stretching hydroxyl groups(wide band at 416 cm?1) and C–O (at 1041 cm?1). For SMBS, twobands at 2922 and 2853 cm?1 were observed which are ascribedas

37、 asymmetric and symmetric stretching vibration of methyleneC–H adsorption bands originated from the alkyl chain of CPC [34].However, no such bands were observed on RBS, which confirmsthe successful impregnation of the CP

38、C onto straw surface. Asfor the oil loaded straw spectrum, these two peaks (2922 and2853 cm?1) were found to be much stronger which suggests theadsorption of oil to hydrophobic, alkyl chain layer on the SMBSsurface.3.2.

39、Dynamic adsorption of oilPreliminary batch adsorption experiments were performed atroom temperature (25 ?C) by mixing a measured amount of RBS andSMBS with emulsified oil solutions for a period of 5 h. The removalpercent

40、ages of the emulsified oil at 3 and 5 h were found to be3.3 ± 0.1% and 2.8 ± 0.1% for RBS and 90.5 ± 1.7% and 90.7 ± 0.9%for SMBS, respectively. The lower removal of the emulsified oil onFig. 1. SEM p

41、hotos of SMBS.Fig. 2. FT-IR spectra of SMBS and oil loaded SMBS.RBS provides a sensible justification in using SMBS as an adsorbentfor the subsequent experiments.Fig. 3 depicts the dynamic oil adsorption as a function of

42、 con-tact time at varying oil concentrations. It was found that the oiladsorption showed an increasing trend with time. The adsorptionconsisted of two significant phases: a primary rapid phase and aslow phase. Most of th